improved error mesages
diff --git a/src/mesa/shader/shaderobjects.c b/src/mesa/shader/shaderobjects.c
index c7a1cec..da4d5c8 100644
--- a/src/mesa/shader/shaderobjects.c
+++ b/src/mesa/shader/shaderobjects.c
@@ -307,14 +307,14 @@
    FLUSH_VERTICES(ctx, _NEW_PROGRAM);
 
    if (programObj != 0) {
-      GET_PROGRAM(pro, programObj, "glUseProgramObjectARB");
+      GET_PROGRAM(pro, programObj, "glUseProgramObjectARB(program)");
 
       if (pro == NULL)
          return;
 
       if ((**pro).GetLinkStatus(pro) == GL_FALSE) {
          RELEASE_PROGRAM(pro);
-         _mesa_error(ctx, GL_INVALID_OPERATION, "glUseProgramObjectARB");
+         _mesa_error(ctx, GL_INVALID_OPERATION, "glUseProgramObjectARB(not linked)");
          return;
       }